一、新建项目、实体类、servlet
1.新建Dynamic Web project，新建过程如下；
2.在src目录下新建两个包，一个命名为entity，一个命名为servlet，新建过程如下；
3.在entity目录下新建两个实体类，一个名为Cake,一个名为CakeDB,新建过程如下：
4.在servlet目录下新建三个servlet，命名分别为ListCakeServlet、PurchaseServlet和CartServlet，新建过程如下：
所有东西建完后结果如图：
二：源代码
1.Cake实体类：
package entity;
public class Cake {
private String id;
private String name;
public Cake() {
}
public Cake(String id, String name) {
this.id = id;
this.name = name;
}
public void setId(String id) {
this.id=id;
}
public String getId() {
return id;
}
public void setName(String name) {
this.name=name;
}
public String getName() {
return name;
}
}
2.CakeDB实体类：
package entity;
import java.util.Collection;
import java.util.LinkedHashMap;
import java.util.Map;
public class CakeDB {
private static Map<String, Cake> cake = new LinkedHashMap<String, Cake>();
static {//模拟数据库中的记录
cake.put("1001", new Cake("1001", "A类：巧克力蛋糕"));
cake.put("1002", new Cake("1002", "B类：水果沙拉蛋糕"));
cake.put("1003", new Cake("1003", "C类：慕斯蛋糕"));
cake.put("1004", new Cake("1004", "D类：奶油蛋糕"));
cake.put("1005", new Cake("1005", "E类：干果蛋糕"));
}
// 获得所有的蛋糕
public static Collection<Cake> getAll() {
return cake.values();
}
// 根据指定的id获蛋糕
public static Cake getCake(String id) {
return cake.get(id);
}
}
3.ListCakeServlet：
package servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Collection;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import entity.Cake;
import entity.CakeDB;
@WebServlet("/ListCakeServlet")
public class ListCakeServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public ListCakeServlet() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse resp)
throws ServletException, IOException {
resp.setContentType("text/html;charset=utf-8");
PrintWriter out = resp.getWriter();
Collection<Cake> cakes = CakeDB.getAll();
out.write("本站提供的蛋糕有：<br>");
for (Cake cake : cakes) {
String url = "PurchaseServlet?id=" + cake.getId();
out.write(cake.getName() + "<a href='" + url
+ "'>点击购买</a><br>");
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
4.PurchaseServlet：
package servlet;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import entity.Cake;
import entity.CakeDB;
@WebServlet("/PurchaseServlet")
public class PurchaseServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public PurchaseServlet() {
super();
}
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// 获得用户购买的商品
String id = req.getParameter("id");
if (id == null) {
// 如果id为null，重定向到ListBookServlet页面
String url = "ListBookServlet";
resp.sendRedirect(url);
return;
}
Cake book = CakeDB.getCake(id);
// 创建或者获得用户的Session对象
HttpSession session = req.getSession();
// 从Session对象中获得用户的购物车
List<Cake> cart = (List) session.getAttribute("cart");
if (cart == null) {
// 首次购买，为用户创建一个购物车(List集合模拟购物车)
cart = new ArrayList<Cake>();
// 将购物城存入Session对象
session.setAttribute("cart", cart);
}
// 将商品放入购物车
cart.add(book);
// 创建Cookie存放Session的标识号
Cookie cookie = new Cookie("JSESSIONID", session.getId());
cookie.setMaxAge(60 * 30);
cookie.setPath("/Servlet");
resp.addCookie(cookie);
// 重定向到购物车页面
String url = "CartServlet";
resp.sendRedirect(url);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
5.CartServlet:
package servlet;
import entity.Cake;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
@WebServlet("/CartServlet")
public class CartServlet extends HttpServlet {
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException{
resp.setContentType("text/html;charset=utf-8");
PrintWriter out = resp.getWriter();
List<Cake> cart = null;
boolean purFlag = true;
HttpSession session = req.getSession(false);
if (session == null)
{
purFlag =false;
}
else {
cart = (List) session.getAttribute("cart");
if (cart == null){
purFlag=false;
}
}
if(!purFlag){
out.write("抱歉，您还没有购买任何商品！<br>");
}
else {
out.write("您购买的蛋糕有：<br>");
double price = 0;
for (Cake cake:cart){
out.write(cake.getName() +"<br>");
}
}
}
}
三、运行
1.在ListCakeServlet文件下运行，点击鼠标右键，选择run as，具体如图:
2.运行结果如图：
点击购买之后跳转CartServlet页面，比如我点了巧克力蛋糕后：
以上就是使用Session和cookie会话对象实现简单购物车功能。希望对你有帮助哦~